Hi,
Welcome to the forum.
Battery life can be variable and 2 years use is often considered reasonable. Some batteries seem to fail pretty quickly whilst others go on and on.
Eventually all batteries begin to show their age and each charge seems to provide shorter and shorter working life.
Before getting a new battery here's some things you can consider:
1 Let your battery drain down to flat and then recharge to 100%, then let it drain down again (leave it on with some programmes or DVD running etc
2 Repeat this process about 3 times, this will help to "condition" your battery and remove the "memory effect" of partial recharges.
3 Check your power saving settings (via Control Panel) to ensure that power saving is optimised
4 Check that screen brightness is set to a reasonable level, (the brighter the screen the higher the battery drain)
5 Check for any items plugged into your machine that are not being used or are unnecessary, for example, pcmcia cards are notorious for sapping power even if nothing is plugged in to them. Some USB stuff is similar
6 Some machines will automatically lower the CPU speed when on battery power, but this can sometimes be switched off for maximum performance, but at the expense of battery life.
7 Screen savers and the like can take up valuable power and often provide very little benefit.
8 The use of sleep mode or hibernate can often prolong the time the machine will run with little battery drain.
I Hope some of these ideas work for you...if not it may be time to consider having your local computer tech test your battery and or provide a new one
Regards
paws